Expression of DNA sequences in a plant host is dependent upon the presence of operably linked regulatory elements that are functional within the plant host. Choice of the regulatory element will determine when and where within the organism the DNA sequence is expressed. Where continuous expression is desired throughout the cells of a plant, and/or throughout development, constitutive promoters are utilized. In contrast, where gene expression in response to a stimulus is desired, inducible promoters are the regulatory element of choice. Where expression in specific tissues or organs are desired, tissue-preferred promoters may be used. That is, they may drive expression in specific tissues or organs. Such tissue-preferred promoters may be temporal, constitutive, or inducible. In either case, additional regulatory sequences upstream and/or downstream from a core promoter sequence may be included in expression constructs to bring about varying levels of expression of nucleotide sequences in a transgenic plant.
As this field develops and more genes become accessible, a greater need exists for transformed plants with multiple genes. These multiple exogenous genes typically need to be controlled by separate regulatory sequences, however. Further, some genes should be regulated constitutively whereas other genes should be expressed at certain developmental stages and/or locations in the transgenic organism. Accordingly, a variety of regulatory sequences having diverse effects is needed.
Diverse regulatory sequences are also needed, as undesirable biochemical interactions can result from using the same regulatory sequence to control more than one gene. For example, transformation with multiple copies of a regulatory element may cause problems, such that expression of one or more genes may be affected.
Isolation and characterization of pericarp-preferred promoters and terminators that can serve as regulatory elements for expression of isolated nucleotide sequences of interest in a pericarp-preferred manner are needed for impacting various traits in plants and in use with scorable markers. The inventor has isolated just such a promoter.